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From: Peter Xu <peterx@redhat.com>
To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Christophe de Dinechin <dinechin@redhat.com>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Yan Zhao <yan.y.zhao@intel.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Kevin Kevin <kevin.tian@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH v3 14/21] KVM: Don't allocate dirty bitmap if dirty ring is enabled
Date: Thu, 9 Jan 2020 11:41:02 -0500
Message-ID: <20200109164102.GA36997@xz-x1> (raw)
In-Reply-To: <20200109145729.32898-15-peterx@redhat.com>

On Thu, Jan 09, 2020 at 09:57:22AM -0500, Peter Xu wrote:
> Because kvm dirty rings and kvm dirty log is used in an exclusive way,
> Let's avoid creating the dirty_bitmap when kvm dirty ring is enabled.
> At the meantime, since the dirty_bitmap will be conditionally created
> now, we can't use it as a sign of "whether this memory slot enabled
> dirty tracking".  Change users like that to check against the kvm
> memory slot flags.
> 
> Note that there still can be chances where the kvm memory slot got its
> dirty_bitmap allocated, _if_ the memory slots are created before
> enabling of the dirty rings and at the same time with the dirty
> tracking capability enabled, they'll still with the dirty_bitmap.
> However it should not hurt much (e.g., the bitmaps will always be
> freed if they are there), and the real users normally won't trigger
> this because dirty bit tracking flag should in most cases only be
> applied to kvm slots only before migration starts, that should be far
> latter than kvm initializes (VM starts).
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  include/linux/kvm_host.h | 5 +++++
>  virt/kvm/kvm_main.c      | 5 +++--
>  2 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index c96161c6a0c9..ab2a169b1264 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -353,6 +353,11 @@ struct kvm_memory_slot {
>  	u8 as_id;
>  };
>  
> +static inline bool kvm_slot_dirty_track_enabled(struct kvm_memory_slot *slot)
> +{
> +	return slot->flags & KVM_MEM_LOG_DIRTY_PAGES;
> +}
> +
>  static inline unsigned long kvm_dirty_bitmap_bytes(struct kvm_memory_slot *memslot)
>  {
>  	return ALIGN(memslot->npages, BITS_PER_LONG) / 8;
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index f0f766183cb2..46da3169944f 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1120,7 +1120,8 @@ int __kvm_set_memory_region(struct kvm *kvm,
>  	}
>  
>  	/* Allocate page dirty bitmap if needed */
> -	if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) {
> +	if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap &&
> +	    !kvm->dirty_ring_size) {
>  		if (kvm_create_dirty_bitmap(&new) < 0)
>  			goto out_free;
>  	}
> @@ -2309,7 +2310,7 @@ static void mark_page_dirty_in_slot(struct kvm *kvm,
>  				    struct kvm_memory_slot *memslot,
>  				    gfn_t gfn)
>  {
> -	if (memslot && memslot->dirty_bitmap) {
> +	if (memslot && kvm_slot_dirty_track_enabled(memslot)) {
>  		unsigned long rel_gfn = gfn - memslot->base_gfn;
>  		u32 slot = (memslot->as_id << 16) | memslot->id;
>  
> -- 
> 2.24.1
> 

I think below should be squashed as well into this patch:

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 621b842a9b7b..0806bd12d8ee 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1308,7 +1308,7 @@ static inline bool memslot_valid_for_gpte(struct kvm_memory_slot *slot,
 {
        if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
                return false;
-       if (no_dirty_log && slot->dirty_bitmap)
+       if (no_dirty_log && kvm_slot_dirty_track_enabled(slot))
                return false;
  
        return true;

Thanks,

-- 
Peter Xu


  reply index

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-09 14:57 [PATCH v3 00/21] KVM: Dirty ring interface Peter Xu
2020-01-09 14:57 ` [PATCH v3 01/21] vfio: introduce vfio_iova_rw to read/write a range of IOVAs Peter Xu
2020-01-09 14:57 ` [PATCH v3 02/21] drm/i915/gvt: subsitute kvm_read/write_guest with vfio_iova_rw Peter Xu
2020-01-09 14:57 ` [PATCH v3 03/21] KVM: Remove kvm_read_guest_atomic() Peter Xu
2020-01-09 14:57 ` [PATCH v3 04/21] KVM: Add build-time error check on kvm_run size Peter Xu
2020-01-09 14:57 ` [PATCH v3 05/21] KVM: X86: Change parameter for fast_page_fault tracepoint Peter Xu
2020-01-09 14:57 ` [PATCH v3 06/21] KVM: X86: Don't take srcu lock in init_rmode_identity_map() Peter Xu
2020-01-09 14:57 ` [PATCH v3 07/21] KVM: Cache as_id in kvm_memory_slot Peter Xu
2020-01-09 14:57 ` [PATCH v3 08/21] KVM: X86: Drop x86_set_memory_region() Peter Xu
2020-01-09 14:57 ` [PATCH v3 09/21] KVM: X86: Don't track dirty for KVM_SET_[TSS_ADDR|IDENTITY_MAP_ADDR] Peter Xu
2020-01-19  9:01   ` Paolo Bonzini
2020-01-20  6:45     ` Peter Xu
2020-01-21 15:56   ` Sean Christopherson
2020-01-21 16:14     ` Paolo Bonzini
2020-01-28  5:50     ` Peter Xu
2020-01-28 18:24       ` Sean Christopherson
2020-01-31 15:08         ` Peter Xu
2020-01-31 19:33           ` Sean Christopherson
2020-01-31 20:28             ` Peter Xu
2020-01-31 20:36               ` Sean Christopherson
2020-01-31 20:55                 ` Peter Xu
2020-01-31 21:29                   ` Sean Christopherson
2020-01-31 22:16                     ` Peter Xu
2020-01-31 22:20                       ` Sean Christopherson
2020-01-09 14:57 ` [PATCH v3 10/21] KVM: Pass in kvm pointer into mark_page_dirty_in_slot() Peter Xu
2020-01-09 14:57 ` [PATCH v3 11/21] KVM: Move running VCPU from ARM to common code Peter Xu
2020-01-09 14:57 ` [PATCH v3 12/21] KVM: X86: Implement ring-based dirty memory tracking Peter Xu
2020-01-09 16:29   ` Michael S. Tsirkin
2020-01-09 16:56     ` Alex Williamson
2020-01-09 19:21       ` Peter Xu
2020-01-09 19:36         ` Michael S. Tsirkin
2020-01-09 19:15     ` Peter Xu
2020-01-09 19:35       ` Michael S. Tsirkin
2020-01-09 20:19         ` Peter Xu
2020-01-09 22:18           ` Michael S. Tsirkin
2020-01-10 15:29             ` Peter Xu
2020-01-12  6:24               ` Michael S. Tsirkin
2020-01-14 20:01         ` Peter Xu
2020-01-15  6:50           ` Michael S. Tsirkin
2020-01-15 15:20             ` Peter Xu
2020-01-19  9:09       ` Paolo Bonzini
2020-01-19 10:12         ` Michael S. Tsirkin
2020-01-20  7:29           ` Peter Xu
2020-01-20  7:47             ` Michael S. Tsirkin
2020-01-21  8:29               ` Peter Xu
2020-01-21 10:25                 ` Paolo Bonzini
2020-01-21 10:24             ` Paolo Bonzini
2020-01-11  4:49   ` kbuild test robot
2020-01-11 23:19   ` kbuild test robot
2020-01-15  6:47   ` Michael S. Tsirkin
2020-01-15 15:27     ` Peter Xu
2020-01-16  8:38   ` Michael S. Tsirkin
2020-01-16 16:27     ` Peter Xu
2020-01-17  9:50       ` Michael S. Tsirkin
2020-01-20  6:48         ` Peter Xu
2020-01-09 14:57 ` [PATCH v3 13/21] KVM: Make dirty ring exclusive to dirty bitmap log Peter Xu
2020-01-09 14:57 ` [PATCH v3 14/21] KVM: Don't allocate dirty bitmap if dirty ring is enabled Peter Xu
2020-01-09 16:41   ` Peter Xu [this message]
2020-01-09 14:57 ` [PATCH v3 15/21] KVM: selftests: Always clear dirty bitmap after iteration Peter Xu
2020-01-09 14:57 ` [PATCH v3 16/21] KVM: selftests: Sync uapi/linux/kvm.h to tools/ Peter Xu
2020-01-09 14:57 ` [PATCH v3 17/21] KVM: selftests: Use a single binary for dirty/clear log test Peter Xu
2020-01-09 14:57 ` [PATCH v3 18/21] KVM: selftests: Introduce after_vcpu_run hook for dirty " Peter Xu
2020-01-09 14:57 ` [PATCH v3 19/21] KVM: selftests: Add dirty ring buffer test Peter Xu
2020-01-09 14:57 ` [PATCH v3 20/21] KVM: selftests: Let dirty_log_test async for dirty ring test Peter Xu
2020-01-09 14:57 ` [PATCH v3 21/21] KVM: selftests: Add "-c" parameter to dirty log test Peter Xu
2020-01-09 15:59 ` [PATCH v3 00/21] KVM: Dirty ring interface Michael S. Tsirkin
2020-01-09 16:17   ` Peter Xu
2020-01-09 16:40     ` Michael S. Tsirkin
2020-01-09 17:08       ` Peter Xu
2020-01-09 19:08         ` Michael S. Tsirkin
2020-01-09 19:39           ` Peter Xu
2020-01-09 20:42             ` Paolo Bonzini
2020-01-09 22:28             ` Michael S. Tsirkin
2020-01-10 15:10               ` Peter Xu
2020-01-09 16:47 ` Alex Williamson
2020-01-09 17:58   ` Peter Xu
2020-01-09 19:13     ` Michael S. Tsirkin
2020-01-09 19:23       ` Peter Xu
2020-01-09 19:37         ` Michael S. Tsirkin
2020-01-09 20:51       ` Paolo Bonzini
2020-01-09 22:21         ` Michael S. Tsirkin
2020-01-19  9:11 ` Paolo Bonzini

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